The present disclosure generally relates to systems and methods for mounting an aircraft engine to an aircraft. More particularly, this disclosure relates to a mounting system and method adapted to reduce backbone deflection that can occur in an aircraft engine as a result of aerodynamic, gravitational, inertial, and thrust loads during aircraft operation.
At least some known gas turbine engines, such as turbofans, include a fan, a core engine, and a power turbine. The core engine includes at least one compressor, a combustor, and a high-pressure turbine coupled together in a serial flow relationship. More specifically, the compressor and high-pressure turbine are coupled through a shaft to form a high-pressure rotor assembly. Air entering the core engine is mixed with fuel and ignited to form a high energy gas stream. The high energy gas stream flows through the high-pressure turbine to rotatably drive the high-pressure turbine such that the shaft rotatably drives the compressor. The gas stream expands as it flows through a power or low-pressure turbine positioned aft of the high-pressure turbine. The low-pressure turbine includes a rotor assembly having a fan coupled to a drive shaft. The low-pressure turbine rotatably drives the fan through the drive shaft. Turbine engine performance is enhanced when the fan operates at a relatively low rotational speed and with a low pressure ratio.
As engine bypass ratios are increased, the larger fan and increased airflow result in higher loads at take-off rotation. A large lift load is created on the engine inlet assembly as internal and some external airflow is turned to align with the engine axis of rotation. This load represents a major contribution to the engine backbone bending moment. The engine thrust also creates a pitching moment depending on whether the focal point of the engine's mounting system is on, above or below the engine center-line. The smaller core diameters associated with increased bypass ratio engines, together with increased pressure ratios and smaller blade heights, make the core engine more sensitive to backbone bending. At least some engines include more open tip clearances, to accommodate backbone bending. However, such open tip clearances may result in a reduction in fuel efficiency.